Charge air system and charge air operation method

Abstract

A charge air system for a combustion engine and an operation method are provided. The charge air system includes a first turbocharger stage for intake of combustion air supplied to the engine from a first pressure to a second pressure, a second turbocharger stage for compression of the compressed air to a third pressure, a first heat exchanger being arranged between the first and the second turbocharger stage for cooling the compressed air, a first intake air bypass for modulating the flow of the air through the first heat exchanger and/or a first mass flow control unit for controlling the flow of a cooling medium supplied to the first heat exchanger.

The invention claimed is: 
     
       1. Charge air system for a combustion engine, comprising
 a first boost system stage for compression of combustion air supplied to the engine from a first pressure to a second pressure 
 a second boost system stage for compression of the compressed air to a third pressure, 
 a first heat exchanger being arranged between the first and the second boost stage for cooling the compressed air, 
 a first intake air bypass connected at or upstream of an inlet to the first heat exchanger and at or downstream of an outlet of the first heat exchanger and comprising a controllable bypass valve for modulating the flow of the air through the first heat exchanger, 
 a first mass flow control unit comprising a controllable valve for controlling flow of a cooling medium supplied to the first heat exchanger, and 
 an electronic control unit configured to control a temperature of air at or downstream of the outlet of the first beat exchanger to maintain temperature of the air at or downstream of the outlet of the first heat exchanger above a dew point temperature of that air by controlling a flow of the air through the first heat exchanger and by controlling the first mass flow control unit to control the flow of the cooling medium supplied to tile first heat exchanger. 
 
     
     
       2. The charge air system according to  claim 1 , wherein a second heat exchanger is provided downstream attic second boost stage between the second boost stage and an intake manifold of the engine. 
     
     
       3. The charge air system according to  claim 1 , wherein a second intake air bypass is provided for modulating the flow of the air through the second heat exchanger. 
     
     
       4. The charge air system according to  claim 3 , wherein at least one of the first and the second intake air bypasses are provided for at least partially bypassing at least one of the first and second heat exchangers. 
     
     
       5. The charge air system according to  claim 3 , wherein at least one of the first and the second intake air bypasses are provided for fully bypassing at least one of the first and second heat exchangers. 
     
     
       6. The charge air system according to  claim 1 , wherein a second mass flow control unit is provided for controlling the flow of a cooling medium supplied to the second heat exchanger. 
     
     
       7. The charge air system according to  claim 6 , wherein an exhaust gas recirculation system is provided for recirculating exhaust gas from an exhaust manifold to the intake manifold of the engine. 
     
     
       8. The charge air system according to  claim 7 , wherein a first exhaust heat exchanger is provided in an exhaust line downstream of the engine for cooling the exhaust gas to a first exhaust heat exchanger temperature that is lower than a temperature of the exhaust gas upstream of the first exhaust heat exchanger. 
     
     
       9. The charge air system according to  claim 7 , wherein a first exhaust bypass is provided for modulating the flow of the exhaust through the first exhaust heat exchanger by at least partially or fully bypassing the first exhaust heat exchanger. 
     
     
       10. The charge air system according to  claim 8 , wherein a third mass flow control unit is provided for controlling the flow of a cooling medium supplied to the first exhaust heat exchanger. 
     
     
       11. The charge air system according to one  claim 10 , wherein a second exhaust heat exchanger is provided in the exhaust line downstream of the engine for cooling the exhaust gas received from the first exhaust heat exchanger to a second exhaust heat exchanger temperature that is lower than the first exhaust heat exchanger temperature. 
     
     
       12. The charge air system according to  claim 11 , wherein a second exhaust bypass is provided for modulating the flow of the exhaust through the second heat exchanger by at least partially or fully bypassing the second exhaust heat exchanger. 
     
     
       13. The charge air system according to  claim 12 , wherein a fourth mass flow control unit is provided for controlling the flow of a cooling medium supplied to the second exhaust heat exchanger. 
     
     
       14. The charge air system according to  claim 13 , wherein the electronic control unit is further configured to control at least one of the amount of air which bypasses at least one of the first heat exchanger and the second heat exchanger, the amount of exhaust gas which bypasses at least one of the first exhaust heat exchanger and the second exhaust heat exchanger and the mass flow of a cooling medium through at least one of the first heat exchanger, second heat exchanger, first exhaust heat exchanger, and second exhaust heat exchanger. 
     
     
       15. The charge air system according to  claim 1 , wherein a sensor unit is provided at a discharge port of the first heat exchanger for estimating, the dew point temperature of the air discharged from the heat exchanger. 
     
     
       16. The charge air system according to  claim 1 , wherein a sensor unit is provided at a discharge port of the second exhaust heat exchanger for estimating the dew point temperature of the exhaust discharged from the heat exchanger.